196 The seven VEGETABLE FAMILIES. 
Camers-hair Pencil. The parts where each Bleb, or Seed-Veflel adhered, 
appear a little rough j Fig. 32. For the reft, the Membrane is tranfparenr, 
and is not feen, unlefs in diftindtion from the more elevated Vcflels j and 
the little Specks, or Rudiments of future Blebs for Seeds. 
The inner Membrane is a mere Film j it only lines the other, and form s- 
the Blebs or Seed-Veflcis. The Seeds of the Truffle, tho’ very dif- 
tindl to powerful Glaftes, are too minute for the management of the Gar- 
dener’s hand in fowing. Probably they fwell greatly when the Truffle 
burfts with ripcnefs : for the Seeds of inoft Mufhrooms do fo. Thofe of 
the Lamellated kinds increafe to fixty or fcventy times their bignefs, after 
they are fallen from the Plant, before they begin to burft for the growth 
©f the included Muftiroom. 
CHAP. XLIII. 
Of the C o N V o L u T E i> ALGA. 
HIS fingular Species will give us as diftindl an inftance of the fecond 
Family of Plants, as the Truffle does of the ftrft. The Charader 
of thefe is to be foliaceous ; and this is foliaceous entirely. 
The common Oistergreen, and the like, are Plants alfo of this 
daft j and it is from thofe natives of the Sea the term Alga has been 
taken, to exprefs the entire Family *. into which, perhaps, fome Plants of 
too complex a ftrutSure have been admitted, even by Writers efteemed the 
moft corred. 
A short defeription will be fufficient to illuftrate this fpecies, the very 
figure of which alone explains all we know of its parts and compofition : 
yet even this, fimple as it is, appears of a fuperior order to thofe plain flat 
kinds before named, whofe whole charader feems to be what the Philofo- 
phers have given as that of matter, Extenfion All Plants merely foliace- 
ous, are Alg^ j this rifes above the plain kinds, by being tubular, and 
elegantly folded. See Plate XV. What are its frudtifications I have fought 
in vain : and tho’ its matter be truly vegetable, perhaps its fingular form is 
owing to a caufe different from that of Vegetation. 
In fome kinds of what are called Metallick Vegetations, the Stems and 
Branches, as they are called, are made by the afeending force of difen- 
tingled air. The bottom of the Veffels is covered with a rude mafs of mi- 
neral matter, from which a bubble of air rifing toward the furface, carries 
with 
